<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Aspect Ratio Example</title>
  <style>
    .container {
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
    }
    .box {
      background-color: lightblue;
      width: 50%;
      aspect-ratio: 16 / 9; /* 宽高比为 16:9 */
    }
  </style>
</head>
<body>
  <div class="container">
    <div class="box"></div>
  </div>
</body>
</html>
